To minimize pollutants produced by internal combustion engines, a portion of the engine exhaust may be recirculated to an intake of the engine. An EGR valve, such as a mixing valve, may be used to assist in directing the portion of the exhaust to the intake. Such valves typically require a great deal of torque for actuation during engine operation. In addition, such valves are often disposed within the engine compartment and, thus, require compact actuation assemblies due to space constraints.
U.S. Pat. No. 3,948,231 issued to Smith (“the '231 patent”) discloses a power and deceleration governor for automotive engines including a butterfly-type mixture control valve. In a first embodiment, the valve is actuated using a rack and pinion assembly driven by a diaphragm motor. In a second embodiment, the valve is actuated using a hydraulic cylinder, and in a third embodiment, the valve is actuated using a clutch drive motor.
While the governors of the '231 patent may be configured to actuate the mixture control valve, each of the disclosed governors are relatively large and cumbersome, and may be difficult to package in a conventional engine compartment. In addition, each of the governors relies on a vacuum system for actuation. Such a system may not supply the requisite torque to open, close, and/or otherwise actuate the mixture control valve in certain engine operating conditions. Moreover, the governors of the '231 patent may not control the mixing valve using an internal feedback mechanism.
The disclosed valve actuation assembly is directed toward overcoming one or more of the problems set forth above.